1. Field of the Invention
The present invention relates to a graph display device for displaying a graph corresponding to a functional expression.
2. Description of the Related Art
Usually, a scientific calculator (a graphing calculator) provided with a graph display function is merchandised as a product. In this calculator, when a user inputs an arbitrary functional expression y=f(x), a graph corresponding to the inputted functional expression is displayed on a display part.
Further, a graphing calculator is thought about in which under a state that a quadratic functional expression of Y=X2+AX−1 is inputted, graphs obtained when a value of a coefficient A is changed are displayed in a display part in order (for instance, patent literature 1: JP-A-9-282475). In this case, a screen exclusively used to set the value of the coefficient A is displayed. In the exclusive screen, a user inputs an initial value (Start), a final value (End) and a change space (Pitch) of the coefficient A.
As described above, usually, when the value of the coefficient included in the functional expression is changed, the exclusive screen needs to be displayed to set the value of the coefficient so as to carry out respectively setting operations of the values. Thus, a troublesome operation is necessary.
Further, in order to change the value or the change space of the coefficient which is set once, a problem arises that the screen needs to be displayed again and the value or the change space needs to be reset, so that it takes extremely much time and labor.
The present invention is devised by considering the above-described problems and it is an object of the present invention to provide a graph display device which can exceedingly simply change a value of a coefficient included in a functional expression and display a graph corresponding to the change when the graph corresponding to the functional expression is displayed.